81349799 has 4 divisors (see below), whose sum is σ = 81492840. Its totient is φ = 81206760.

The previous prime is 81349789. The next prime is 81349823. The reversal of 81349799 is 99794318.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81349799 - 2²⁰ = 80301223 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81349739) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 70664 + ... + 71805.

It is an arithmetic number, because the mean of its divisors is an integer number (20373210).

Almost surely, 2^81349799 is an apocalyptic number.

81349799 is a deficient number, since it is larger than the sum of its proper divisors (143041).

81349799 is a wasteful number, since it uses less digits than its factorization.

81349799 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143040.

The product of its digits is 489888, while the sum is 50.

The square root of 81349799 is about 9019.4123422760. The cubic root of 81349799 is about 433.2968130301.

The spelling of 81349799 in words is "eighty-one million, three hundred forty-nine thousand, seven hundred ninety-nine".